Anesthesia is a process commonly used to block the perception of pain. The first public demonstration of administering an anesthetic agent occurred over 150 years ago when diethyl ether was utilized during a surgical operation to remove a tumor. Today, anesthetic agents are utilized in patient procedures across the medical specialties.
Anesthetic agents are used in procedures carried out on various tissues and organs. For example, with regard to procedures performed on the eye, common anesthetic agents utilized include subconjunctival injections of aqueous lidocaine and tetracaine drops. However, subconjunctival injections of aqueous lidocaine are less than desirable as many patients suffer from anxiety caused by needle phobia and/or the physical pain caused by the actual injection. Indeed, it is believed that the anxiety levels can reach the point where patients avoid the necessary medical care. The topical administration of tetracaine drops avoids these needle-related problems. However, there are some drawbacks with such drops. Some of the drops administered to patient may miss the eye due to the shaking of the hand or the blinking of the eye. The residence time of the drop on the eye is limited, for example, less than about a minute. Thus, the anesthetic efficacy of the tetracaine drops could become insufficient since both the onset of anesthesia is not rapid, and the duration of anesthetic activity is limited. Some of the formulations reported to be sterile do not specify the particle size limits. In addition, tetracaine may also be toxic to the cornea. Thus, there is a desire for other, more efficacious anesthetic formulations for topical administration, especially formulations which cause less anxiety, pain, and provide both rapid onset and prolonged anesthetic activity.
The invention provides such an anesthetic formulation. These and other advantages of the invention, as well as additional inventive features, will be apparent from the description of the invention provided herein.